<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    {{num}}
    <br>
     <button @click="doubleNum = 50">给计算属性赋值</button>
    {{doubleNum}}
  </div>
  <script src="./vue.global.js"></script>
  <script>
    const { createApp } = Vue;
    const app = createApp({
      data(){
        return {
          num: 10
        }
      },
     
      computed: {
        doubleNum: {
          get(){
            return this.num * 2
          },
          set(val) {
            console.log(val, 222);
            this.num = val / 2;
          }
        }
      }
    })
    app.mount('#app')
  </script>
</body>
</html>